Suction cylinder mold for papermaking machines



Sept. 14; 1943'. M. ca. R. NEWBOULD 2,329,553

SUCTION CYLINDER MOLD FOR PAPER MAKING MACHINES Filed March 7, 194;

/j a 'Iwwi/ Patented Sept. 14, 1943 r sUo'rrori'o YL NnER Motn ro'rt:JMaurice George Itobert Newbouldrllondon, Eng;

AKING MACHINES land, assignorf-to PapercreteL-imited, London,: 1

England Thisin've ntion relates to, the production ot felted fibrousmaterial in sheetform and more particularly felted cellulosic fibrousmaterial of the character employed in forming paper, paper Pulp and thelike. i

plying suction to a predetermined area 'ofthe 1 pulp whichis aspiratedagainst the surface of the foraminous member, "the suction operating toremove water therefrom. K I

In known apparatus bfthfl above'kind' both a watersuction-chamber and anairsuction cham her are employed. The object of th water 'suc' tionchamber is to draw the fibre against the submerged outer surface of theforaminous mem-' ber where the fibre is retained to form the sheet, andthe water that carried the-fibre is separated fromit by passing throughthe foraminous memberand subsequently out ofthe machine. The air suctionchamber operates to withdrawthe water and consolidate the depositedmaterial after it has passed the-water suction area, that is to say,when the'fibrous sheet has emerged from the stuii tank. Undernormalconditions the sheet is required in as dry and consolidated acondition as possible, andthe twovmain essentials for the air suctionchamber arethus time and the highest degree of suction obtainable. Thewater suction chamber, however, rarely works above a suction value of 25cm. of mercury, for above this vacuum the increase in thickness ofdeposit is slow and not worth the pumping expense, while the texture ofthe sheet on its outer side is not satisfactory. Hence When using acommon air and water suction chamberwhere the vacuum is equal for bothforming and drying, the air drying portion is usually adverselycontrolled by the conditions obtaining in the water suction portion.

In general a coarse or fast stuff will build up rapidly and with a' low.water suction, whil a slow stuff builds "up slowly and by clogging the.

web and the foraminous member builds up a'high suction without producingproportions to increase in the thickness of the sheet. There is thus .3

maximum and probablyuneconomic thickness which can be produced by anyparticular stuff with existing construction of apparatus, whichcan-only-be governed by variationsin speed. The I invention is directedto the provision of means whereby 'the'limitation set by existingapparatus may be overcome. Y According to the invention; within theforeminous member there is provideda normally stationary member capableof adjustment by rota tion about the 'axisof rotation of the foraminousmember'andoon'sisting of a segmentofa cylinder spaced a convenientdistance from'th'e inne r-surface ofthe cylinder forming part ofthe'fo'raminous membenjfurnished with flanges presenting bearingsurfaces to the interior of the foraminous member and constitutingpartitions dividingfthe spacebetween the segment and-the cylinderforming part of the foraminous memberinto convenient siz'edcompartments, one at least of which is connected to means foraspiratingair through the material deposited on the foraminous mombe'r toflefie'ctits de watering and-that within the cylinder segmentthere is provided ahollow centralshaft from which a suction channel descends toa pointcloseto the inner surface ofthe foraminous "member, "Sl.10h iSUCtlOIlchannel being designed to 'bjCOllIlBCtCd with apump adapted to cause thepulp in which the foraminous mem ber.{ is submerged to be sucked againstthe idramin'o'us member and thus become deposited thereon, the segmentofa cylinder being capable of rotation about the hollow central shaft toadjust the area of the foraminous memberwhich'is subjected to suction,to secure the deposition on it of the 'fibrouspulp, and to vary thearea'of the deposited pulp to efiect'its-dewatering before being carriedinto the position where the de-watered' material willbe brought intoposition against a compartment 1i communicating with the atmosphere ora-seurce-er air pressure to assist in the removal ofthe depositedmaterial-fromthe foraminous member. I The foraminous member may consistof a hol-, low cylinder suitably mounted uponend plates which constitutethe bearings upon which it re .volveson an inner stationary member. Theinner edge to produce corrugated sheeting, or other desired profiles.Holes are provided between the slots in the wall of the cylinder toenable the sieve to be submitted to the various conditions required andwhich are produced by the foraminous member revolving over the chambersof the stationary inner member.

The normally stationary member consists of a segment of a cylinderspaced at a convenient distance from the inner surface of the cylinderforrning part of .the foraminous member, and is flanged v der secured toend plates 2 and 2a formed with at its extremities to present a bearingsurface/co trunnions 3 and 3a on the latter of which is the interior ofthe foraminous member. The annular chamber so formed is subdivided intothree or, if desired, four convenientsized compartments by axialpartitions extending to the inner side of the foraminous member.

This cylinder segment is mounted on a hollow central shaft from which asuction channel descends vertically until close to the inner surfaceofthe foraminousmember. It is upon the hollow shaft that the bearings ofthe end plates of. the foraminous member rotate- These threecompartments provided'bythe normally'stationary membentogether with thecontinuously revolving. foraminousmember, constitute the aspiratingsuction chamberwhich is submergedin the stuif supply tank, the airdrying and consolidating chamber and the normal air pressure chamber. Insome case a fourth chem-- bersuppli'ed with super pressureair isdesirable, and this would be situated between the consolidating chamberand the normal air pressure chamber. I Th aspiration in. the suctionchamber is. operated by a centrifugal pump or the like drawing the waterin whichthe fibrous material was suspended through the sieve and thenceout of the machine by way of the vertical suction. channel and thehollow central shaft. The web so formed is carried by the revolvingforaminous. member out of the stuff tank and across the first axialpartition, of the stationary member to the air dryingand-consolidatingchamber that is main.- tained at a suitable sub-atmospheric pressure bymeans of a vacuum pump or the like. Evacuation of water which wouldaccumulate in this chamber is effected by agravitational by-pass. pipeextending between the higher and the lower two extremities of thechamber and by arranging a suction pipe at'the bottom. of the lowerextremity of the chamber. Continuing its rotation, thev foraminousmember carrying its now partially dried web passesover the secondpartition of the stationary member to theatmospheric pressure chamber,where the web is carried away from the foraminous support to theconsolidating rolls.

The third axial partition forms the-separator between the atmosphericpressure chamber. and the aspirating suction chamber- When varyingcauses, such as fragility of the webor excessive adhesion of the web tothe. foraminous member, necessitate assistance for its removal, a small.super pressure chamber supplied with compressed air is introducedbetween the consolidating-and atmospheric pressure chambers.

For rotating the adjustable stationary member about the shaft in orderto vary-the area to which suction is applied tothe immersed. portiion ofthe foraminous support, any suitable: means may be provided. Thus, forinstance, aprodeeting part of the hollow shaftextending through thebearing. on. one of the end plates of therotating foraminous support mayhe, formed with a worm gear meshing with a worm on a spindle providedwith a hand wheel.

The invention will be described further in detail and by way of examplewith reference to the accompanying drawing, in which:

Figure 1 is a view insectional elevation of a rotatable foraminousmember on a plane contalning theaxis of rotation thereof, and

Figure 2 is a view in section on a plane at right angles to the plane ofsection of Figure 1.

In the drawing, l is a foraminous hollow cylinshown secured a toothedwheel 4 whereby it may be rotated.

About the cylinder and in slots in the end plates there. are arranged aplurality of strips 5 which 'ifunction as a support for a metal wiregauze 6.

These strips as may be seen are tapered axially to facilitate thetightening up of the metal wire gauze. The strips are interchangeableand may have straight exterior edges for the production of plainsheeting or corrugated exterior edges to produce corrugated sheeting.

Within the cylinder in question. there is provided an adjustablesegmental cylinder comprising a member 1. constituting the peripheralwalls thereof and end plates 8, 8a.

v The segmental cylinder is. at each end furnished with flanges 9 and 9atov present a bearing surface to the interior of theforaminous cylinderand the generally annular chamber between the inner and outer cylindersis subdivided in effect into three compartments by radial partitions 10.The wall, however, of the inner cylinder is cut away at the positionindicated by H.

This cylinder is. integral with hollow trunnions or stub shafts l2 and12a and it is upon these that the trunnions of the outer foraminousmember rotate. One of the trunnions or stub shafts of the segmentalcylindrical member is furnished with a worm wheel 13 in engagement witha worm M by which it may be rotated within limits about its axis. inorder that the area of. aspirated pulp subjected to suction beneath thebody of the pulp may be varied as desired.

Secured within the inner chamber there is arranged a. tubular shaft l5from which a suction channel It descends vertically, the end of it beingbrought close to the inner surface of the foraminous member, the tubularshaft being arranged in communication with a pump. 7 In order'to permitthe escape of water from the suction space II intervening betweentwoadiacent radial partitions, whatever may be the posl-. tion intowhich the member I has been rotated relative to the channel N, there areprovided av gravitational by-Dass pipe or pipes l8 extending from oneside to the other of the air suction space which is in communication byway of the pipe l9v with the pipe '20. I

With the. above-described arrangement, if the foraminous support isrevolved at a constant speed in a constant stuff, assuming that thewater suction is constant, a sheet will be delivered of a constantthickness. For example, let it be sup-' posed that the sheet is 50% toothick, then by increasing the speed by 56% or more the right thicknesswill be secured, the drying time will be cut down, and delivery will beincreased. If, on the other hand, the speed is left constant and theadjustable stationary member is displaced in the same direction as thatin which the foraminous support revolves, for instance through an arerepresenting 33 /3% or more of the length of the suction chamber, thenthe time of submersion in the stuff tank is reduced in the requiredproportion. With such an arrangement the end of the suction chamberremote from the first felting may be raised above the stuff level but noair leak can take place here on'account of the sheet formed on therevolving foraminous support when that portion was previously submerged.If desirable the stuff level may be reduced by a weir on the stuff tankalthough this is not essential.

Having now arranged to produce a wet web of the best economic thicknessand at a constant speed, multiples of this thickness can be produced bya series of similar machines situated in line with, but higher andbehind, each preceding machine, so that the web produced by each machinelies upon that produced by the preceding machine, thereby partiallyconsolidating the webs together by suction.

Alternatively, with such a bank of machines all revolving at the samerate, an ultimate composite web could be produced of differentthicknesses of diflerent or the same fibre by adjusting the individualaspirating suction chambers. In certain instances it may be desirable toemploy a construction in which the previously mentioned adjustablestationary member consists of a permanently fixed vertical suctionchannel and hollow horizontal shaft, while the air drying andconsolidating chamber, together with the atmospheric air pressurechamber, are constructed as a saddle member pivoting upon the fixedhollow shaft, the saddle being displaceable by means similar to thosepreviously described. By maintaining the suction channel in the verticalposition the minimum of dead water is left in the aspirating suctionchamber. 1

The adjustment of the stationary member may be effected either when themachine is running or when it is stationary.

Similarly a reduction in the aspirating suction chamber may be effectedby constructing the saddle member of two sections separated in thevertical axial plane by a mechanical device capable of widening ornarrowing the space between them, and so altering the are subtending thesuction area or by other like mechanical devices.

At this point it may be mentioned that so-called suction rollers havebeen used in connection with apparatus of the kind in which a web offibrous pulp is deposited upon a flexible carrier the suction rollerbeing employed for extracting water from the material so deposited, andthat in apparatus of the general type to. which the invention relates,that is to say of the kind including a rotatable foraminous memberadapted to be partially submerged in a body of fibrous pulp and, inassociation with the foraminous member, means for applying suction toapredetermined area of the pulp which is aspirated against the surfaceof the foraminous member, the suction operating to remove watertherefrom, means has been provided for varying the area of a foraminousmember actually immersed in or in contact with the body of fibrous pulp,and which is subjected to suction in order to cause the fibrouscomponent to be deposited on the foraminous member.

I claim: Q

Apparatus for the production of felted fibrous material in sheet formcomprising an outer hollow cylinder having a foraminous peripheral wallsecured to end plates formed with hollow trunnions, a tubular shaftextending through one of said trunnions and terminating within a drum ina suction channel descending substantially downward, the open end ofwhich suction channel is adjacent to the foraminous wall, the saidtubular shaft being designed to be connected with a pump by which theliquid component of the fibrous pulp may be aspirated through theforaminous wall and the fibrous component of the pulp directly-depositedthereon, a segmental cylinder within the drum comprising a memberconstituting the peripheral walls thereof and flanges on the segmentalcylinder at each end presenting a bearingsurface to the interior of theouter cylinder having a foraminous peripheral wall, partition membersextending radially from the segmental cylinder to the foraminousperipheral wall of the hollow cylinder and dividing the space betweenthe inner and outer cylinders into a plurality of chambers each of whichis a segment of an annulus, trunnions on the end plate of the innersegmental cylinder rotatable within the hollow trunnions of the outer.cylinder and on the tubular shaft at one end and at the other end on atubular member adapted to be connected to an air pump for securing afurther extraction of water and thus the drying of the deposited fibrousmaterial and furnished with at least one connection extending from it toone of the chambers between the outer cylinder and the inner segmentalcylinder.

MAURICE GEORGE ROBERT NEWBOULD.

